Method for logging and reporting information on interference by idc terminal in wireless communication system and device for supporting same

ABSTRACT

A method for logging and reporting IDC interference information is provided. The method includes receiving an IDC interference measurement configuration from a network, the IDC interference measurement configuration comprising information instructing that a logging of IDC interference information be started, performing first IDC interference measurement on a first subframe, logging first IDC interference information comprising a first IDC interference measurement result, performing second IDC interference measurement on a second subframe, logging second IDC interference information comprising a second IDC interference measurement result, and reporting the first IDC interference information and the second IDC interference information to the network.

TECHNICAL FIELD

The present invention relates to wireless communication and, moreparticularly, to a method for logging In-Device Coexistence (IDC)interference information about IDC UE and reporting the log and anapparatus supporting the same.

BACKGROUND ART

3^(rd) Generation Partnership Project (3GPP) Long Term Evolution (LTE),that is, the improvement of an LTE Universal Mobile TelecommunicationsSystem (UMTS), has been introduced as 3GPP release 8. 3GPP LTE usesOrthogonal Frequency Division Multiple Access (OFDMA) in downlink anduses Single Carrier-Frequency Division Multiple Access (SC-FDMA) inuplink. 3GPP LTE adopts Multiple Input Multiple Output (MIMO) having amaximum of 4 antennas. Recently, 3GPP LTE-Advanced (LTE-A), that is, theevolution of 3GPP LTE, is being discussed.

A Minimization Drive Test (MDT) is that service providers perform a testusing UE instead of a vehicle for coverage optimization. Coverage variesdepending on the location of a BS, the deployment of peripheralbuildings, and a user use environment. Accordingly, a service providerneeds to periodically perform a driving test, and lots of costs andresources are consumed. An MDT is that a service provider measurescoverage using UE.

An MDT can be divided into a logged MDT and an immediate MDT. Inaccordance with the logged MDT, UE performs MDT measurement and thentransfers logged measurement to a network at a specific point of time.In accordance with the immediate MDT, UE performs MDT measurement andthen transfers measurement to a network when a report condition issatisfied. In the logged MDT, MDT measurement is performed in an RRCidle mode, whereas in the immediate MDT, MDT measurement is performed inan RRC connected mode.

A service provider can write a coverage map, indicating whether or notservice is possible over the entire area to which service is provided bya service provider and a distribution of QoS, by synthesizing pieces ofMDT measurement received from several pieces of UE and use the writtencoverage map in network operations and optimization. For example, when areport on a coverage problem for a specific area is received from UE, aservice provider can enlarge the coverage of a corresponding area cellby increasing the transmission power of a BS that provides service tothe corresponding area.

Meanwhile, a recent UE device supports other wireless communicationtechniques, such as a WLAN (Wi-Fi), WiMAX, Zigbee, Bluetooth and/or aGlobal Navigation Satellite System (GNSS) as well as a wirelesscommunication system, such as LTE. If such UE is In-Device Coexistence(IDC) UE, the transmission and reception of radio signals by anotherwireless communication can generate interference with the transmissionand reception of LTE radio signals and vice versa. This may result in aproblem in that quality of service provided to UE is deteriorated andefficiency of radio resources is also deteriorated.

Meanwhile, a network can make IDC interference avoided by controllingthe operation of UE if it can obtain information about IDC interferencewithin the UE. Accordingly, there is a need for a method for logging IDCinterference information about IDC UE and reporting the logged IDCinterference information to a network.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method for loggingIn-Device Coexistence (IDC) interference information about IDC UE andreporting the log and an apparatus supporting the same.

Technical Solution

In an aspect, a wireless apparatus is provided. The wireless apparatusincludes a first Radio Frequency (RF) unit transmitting and receivingradio signals according to a first wireless communication system, asecond RF unit transmitting and receiving radio signals according to asecond wireless communication system, and a processor operably coupledto the first RF unit. The processor is configured to receive anIn-Device Coexistence (IDC) interference measurement configuration froma network, wherein the IDC interference measurement configurationcomprises information instructing that a logging of IDC interferenceinformation be started, perform first IDC interference measurement on afirst subframe, log first IDC interference information comprising afirst IDC interference measurement result, perform second IDCinterference measurement on a second subframe, log second IDCinterference information comprising a second IDC interferencemeasurement result, and report the first IDC interference informationand the second IDC interference information to the network.

The IDC interference measurement configuration may further includeinformation indicative of a log report type.

If the log report type indicates a non-real-time log report type, thefirst IDC interference information and the second IDC interferenceinformation may be together reported to the network after a specificpoint of time.

The IDC interference measurement configuration may further includelogging interval indication information indicative of the specific pointof time.

The reporting the first IDC interference information and the second IDCinterference information to the network may include receiving a logreport request from the network, and sending the first IDC interferenceinformation and the second IDC interference information to the networkin response to the log report request.

If the log report type indicates a real-time log report type, the firstIDC interference information and the second IDC interference informationmay be individually logged and individually reported to the network.

The first IDC interference information may further include informationabout timing of the first IDC interference measurement.

The information about the timing of the first IDC interferencemeasurement may be timing information of a subframe unit.

The first RF unit and the processor may support Long Term Evolution(LTE) wireless communication.

The second RF unit may support at least one of WLAN (Wi-Fi), WiMAX,Zigbee, and Bluetooth wireless communications.

In another aspect, a method for logging and reporting In-DeviceCoexistence (IDC) interference information, performed by IDC UE, in awireless communication system is provided. The method includes receivingan In-Device Coexistence (IDC) interference measurement configurationfrom a network, the IDC interference measurement configurationcomprising information instructing that a logging of IDC interferenceinformation be started, performing first IDC interference measurement ona first subframe, logging first IDC interference information comprisinga first IDC interference measurement result, performing second IDCinterference measurement on a second subframe, logging second IDCinterference information comprising a second IDC interferencemeasurement result, and reporting the first IDC interference informationand the second IDC interference information to the network.

The IDC interference measurement configuration may further includeinformation indicative of a log report type.

If the log report type indicates a non-real-time log report type, thefirst IDC interference information and the second IDC interferenceinformation may be together reported to the network after a specificpoint of time.

The IDC interference measurement configuration may further includelogging interval indication information indicative of the specific pointof time.

The step of reporting the first IDC interference information and thesecond IDC interference information to the network may include receivinga log report request from the network, and sending the first IDCinterference information and the second IDC interference information tothe network in response to the log report request.

If the log report type indicates a real-time log report type, the firstIDC interference information and the second IDC interference informationmay be individually logged and individually reported to the network.

The first IDC interference information may further include informationabout timing of the first IDC interference measurement.

Advantageous Effects

UE can effectively log an in-device interference situation and anoperation situation over a network and report the logged in-deviceinterference and operation situations to the network. The network canperform a configuration for minimizing the in-device interference of theUE on the UE because the network can obtain information about thepattern of a subframe in which interference can be generated byanalyzing the log. Accordingly, service efficiency and radio resourceefficiency of IDC UE can be improved.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a wireless communication system to which the presentinvention is applied.

FIG. 2 is a block diagram showing a radio protocol architecture for auser plane.

FIG. 3 is a block diagram showing a radio protocol architecture for acontrol plane.

FIG. 4 is a flowchart illustrating the operation of UE in the RRC_idlestate.

FIG. 5 is a flowchart illustrating a process of setting up an RRCconnection.

FIG. 6 is a flowchart illustrating a process of reconfiguring an RRCconnection.

FIG. 7 is an exemplary diagram showing a radio link failure.

FIG. 8 is a flowchart illustrating the success of a connectionreestablishment process.

FIG. 9 is a flowchart illustrating the failure of a connectionreestablishment process.

FIG. 10 is a flowchart illustrating an existing method of performingmeasurement.

FIG. 11 shows an example in which a measurement identity is deleted.

FIG. 12 shows an example in which a measurement object is deleted.

FIG. 13 is a flowchart illustrating an existing measurement procedure.

FIG. 14 is a flowchart illustrating a method of performing a logged MDT.

FIG. 15 is a diagram showing an example of logged MDT measurementaccording to a logging area.

FIG. 16 is a diagram showing an example of logged MDT measurementaccording to a change of RAT.

FIG. 17 is a diagram showing an example of logged measurement.

FIG. 18 is a diagram showing an example of an immediate MDT.

FIG. 19 shows a situation in which mutual interference can be generatedin an IDC environment in which LTE, GPS, and BT/Wi-Fi coexist within apiece of UE.

FIG. 20 is a flowchart illustrating a method for logging IDCinterference information and reporting the log in accordance with anembodiment of the present invention.

FIG. 21 is a diagram showing an example of a method of logginginterference information and reporting the log in an IDC environment towhich an embodiment of the present invention has been applied.

FIG. 22 is a block diagram showing a radio device in which an embodimentof the present invention can be implemented.

MODE FOR INVENTION

FIG. 1 shows a wireless communication system to which the presentinvention is applied. The wireless communication system may also becalled an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) or aLong Term Evolution (LTE)/LTE-A system.

The E-UTRAN includes a Base Station (BS) 20 which provides UserEquipment (UE) 10 with a control plane and a user plane. The UE 10 maybe fixed or may have mobility. The UE 10 may be called another term,such as a Mobile Station (MS), a User Terminal (UT), a SubscriberStation (SS), a Mobile Terminal (MT), or a wireless device. The BS 20refers to a fixed station communicating with the UE 10 and may be calledanother term, such as an evolved-NodeB (eNB), a Base Transceiver System(BTS), or an access point.

The BSs 20 may be interconnected through an X2 interface. The BS 20 isconnected to an Evolved Packet Core (EPC) 30 through an S1 interface,more particularly, to a Mobility Management Entity (MME) through anS1-MME and a Serving Gateway (S-GW) through an S1-U.

The EPC 30 includes the MME, the S-GW, and a Packet Data Network-Gateway(P-GW). The MME has access information about UE or information about thecapabilities of UE. Such information is chiefly used in the mobilitymanagement of UE. The S-GW is a gateway having an E-UTRAN as an endpoint, and the P-GW is a gateway having a PDN as an end point.

The layers of a radio interface protocol between UE and a network may beclassified into L1 (first layer), L2 (second layer), and L3 (thirdlayer) based on lower 3 layers of an Open System Interconnection (OSI)reference model which is widely known in communication systems. Fromamong the layers, the PHY layer belonging to the first layer providesinformation transfer service using physical channels, and a RadioResource Control (RRC) layer placed in the third layer functions tocontrol radio resources between UE and a network. To this end, the RRClayer exchanges RRC messages between UE and a BS.

FIG. 2 is a block diagram showing a radio protocol architecture for auser plane. FIG. 3 is a block diagram showing a radio protocolarchitecture for a control plane. A data plane is a protocol stack foruser data transmission, and a control plane is a protocol stack forcontrol signal transmission.

Referring to FIGS. 2 and 3, a physical (PHY) layer provides a higherlayer with information transfer service using physical channels. The PHYlayer is connected to a Medium Access Control (MAC) layer, that is, ahigher layer, through a transport channel. Data is moved between the MAClayer and the PHY layer through the transport channel. The transportchannel is classified depending on how data is transmitted through aradio interface according to what characteristics.

Data is transferred between different PHY layers, that is, between thePHY layers of a transmitter and a receiver, through a physical channel.The physical channel may be modulated according to an OrthogonalFrequency Division Multiplexing (OFDM) scheme, and the physical channeluses the time and frequency as radio resources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing/de-multiplexing to a transportblock that is provided to a physical channel on the transport channel ofan MAC Service Data Unit (SDU) that belongs to a logical channel. TheMAC layer provides service to a Radio Link Control (RLC) layer through alogical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three operation modes: a Transparent Mode (TM), anUnacknowledged Mode (UM), and an Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The functions of a Packet Data Convergence Protocol (PDCP) layer in theuser plane include the transfer, header compression, and ciphering ofuser data. The functions of the PDCP layer in the user plane include thetransfer and ciphering/integrity protection of control plane data.

The Radio Resource Control (RRC) layer is defined only in the controlplane. The RRC layer is related to the configuration, re-configuration,and release of RBs and responsible for control of logical channels,transport channels, and physical channels. An RB means a logical paththat is provided by the first layer (PHY layer) and the second layers(the MAC layer, the RLC layer, and the PDCP layer) for the transfer ofdata between UE and a network.

What an RB is configured means a process of regulating thecharacteristics of a radio protocol layer and channel and configuringeach detailed parameter and operation method in order to providespecific service. An RB may be divided into a Signaling RB (SRB) and aData RB (DRB). The SRB is used as a passage along which an RRC messageis transported in the control plane, and the DRB is used as a passagealong which user data is transported in the user plane.

If an RRC connection is established between the RRC layer of UE and theRRC layer of an E-UTRAN, the UE is in an RRC connected state. If not,the UE is in the RRC_idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through a downlink SCH or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or a control message is transmitted.

Logical channels placed over a transport channel and mapped to thetransport channel include a broadcast control channel (BCCH), a pagingcontrol channel (PCCH), a common control channel (CCCH), a multicastcontrol channel (MCCH), a multicast traffic channel (MTCH), and so on.

A physical channel includes several OFDM symbols in a time domain andseveral subcarriers in a frequency domain. One subframe consists of aplurality of OFDM symbols in the time domain. A resource block is aresource allocation unit, and a resource block consists of a pluralityof OFDM symbols and a plurality of subcarriers. Furthermore, eachsubframe may use specific subcarriers of specific OFDM symbols (e.g.,the first OFDM symbol) of a corresponding subframe for a physicaldownlink control channel (PDCCH), that is, an L1/L2 control channel. ATransmission Time Interval (TTI) is a unit time for subframetransmission.

An RRC state and RRC connection method of UE are described below.

An RRC state means whether or not the RRC layer of UE has been logicallyconnected with the RRC layer of an E-UTRAN. If the RRC layer of UE islogically connection with the RRC layer of an E-UTRAN, it is called theRRC_connected state. If the RRC layer of UE is not logically connectionwith the RRC layer of an E-UTRAN, it is called the RRC_idle state. SinceUE in the RRC_connected state has an RRC connection, an E-UTRAN maycheck the presence of the UE in a cell unit, and thus the UE may beeffectively controlled. In contrast, an E-UTRAN cannot check UE in theRRC_idle state, and UE in the RRC_idle state is managed by a CoreNetwork (CN) in a tracking area, that is, an area unit greater than acell. That is, the presence of UE in the RRC_idle state is checked in alarger area unit, and the UE in the RRC_idle state needs to move to theRRC connected state in order to receive common mobile communicationservice, such as voice or data.

When a user first powers on UE, the UE first searches for a suitablecell and remains in the RRC_idle state in a corresponding cell. UE inthe RRC_idle state establishes an RRC connection with an E-UTRAN throughan RRC connection procedure when it needs to establish the RRCconnection and shifts to the RRC_connected state. A case where the UE inthe RRC_idle state needs to establish the RRC connection includesseveral cases. For example, the UE in the RRC_idle state establishes anRRC connection when it needs to send uplink data for a reason, such as acall attempt by a user, or when it sends a message in response to apaging message received from an E-UTRAN.

A Non-Access Stratum (NAS) layer placed over the RRC layer performsfunctions, such as session management and mobility management.

In order to manage the mobility of UE in the NAS layer, two states: EPSMobility Management-REGISTERED (EMM-REGISTERED) and EMM-DEREGISTERED aredefined. The two states are applied to UE and an MME. Initial UE is inthe EMM-DEREGISTERED state. In order for the UE to access a network, theUE performs a process of being registered with the network through aninitial attach procedure. If the attach procedure is successfullyperformed, the UE and the MME become the EMM-REGISTERED state.

In order to manage signaling connection between UE and an EPC, twostates: an EPS Connection Management (ECM)-IDLE state and anECM-CONNECTED state are defined. The two states are applied to UE and anMME. If UE in the ECM-IDLE state establishes an RRC connection with anE-UTRAN, the UE becomes the ECM-CONNECTED state. If an MME in theECM-IDLE state establishes an S1 connection with the E-UTRAN, the MMEbecomes the ECM-CONNECTED state. When UE is in the ECM-IDLE state, anE-UTRAN does not have context information about the UE. Accordingly, theUE in the ECM-IDLE state performs a mobility-based procedure based UE,such as cell selection or cell reselection, without a need to receive acommand from a network. In contrast, when UE is in the ECM-CONNECTEDstate, the mobility of the UE is managed by a command from a network. Ifthe location of UE is different from a location known to a network inthe ECM-IDLE state, the UE informs the network of the location of the UEthrough a tracking area update procedure.

System information is described below.

System information includes essential information that needs to be knownby UE in order to access a BS. Accordingly, the UE needs to havereceived all pieces of system information before accessing the BS andneeds to always have recent system information. Furthermore, systeminformation is information that needs to be known by all pieces of UEwithin one cell, and thus a BS periodically transmits the systeminformation.

In accordance with Paragraph 5.2.2 of 3GPP TS 36.331 V8.7.0 (2009-09)“Radio Resource Control (RRC); Protocol specification (Release 8)”,system information is classified into a Master Information Block (MIB),a Scheduling Block (SB), and a System Information Block (SIB). The MIBenables UE to know the physical configuration of a corresponding cell,for example, a bandwidth. The SB informs information about thetransmission of SIBs, for example, a transport period. The SIB is acollection of pieces of correlated system information. For example, anySIB includes only information about neighboring cells, and any SIBincludes only information about an uplink radio channel used by UE.

In general, service provided from a network to UE may be classified intothree types as follows. Furthermore, UE differently recognizes the typeof cell depending on what service may be received. A service type isfirst described, and the type of cell is then described.

1) Limited service: this service provides an emergency call and anEarthquake and Tsunami Warning System (ETWS), and this service can beprovided by an acceptable cell.

2) Normal service: this service means public use for common purposes,and this service can be provided by a suitable or normal cell.

3) Operator service: this service means service for a communicationnetwork service provider, and this cell can be used only by acommunication network service provider, but cannot be used by a commonuser.

In relation to a service type provided by a cell, the type of cell canbe classified as follows.

1) Acceptable cell: a cell from which UE can be provided with limitedservice. This cell is a cell which is not barred from a viewpoint ofcorresponding UE, but satisfies a cell selection criterion for the UE.

2) Suitable cell: a cell from which UE can be provided with suitableservice. This cell satisfies a condition for an acceptable cell and alsosatisfies an additional condition. The additional condition includesthat this cell needs to belong to a Public Land Mobile Network (PLMN)accessible to corresponding UE and this cell must be a cell on which atracking area update procedure is not barred from being executed by UE.If a corresponding cell is a CSG cell, the CSG cell needs to be a cellthat UE can access as a CSG member.

3) Barred cell: a cell that broadcasts that this cell is a cell barredthrough system information.

4) Reserved cell: a cell that broadcasts that this cell is a cellreserved through system information.

FIG. 4 is a flowchart illustrating the operation of UE in the RRC_idlestate. FIG. 4 shows a procedure in which UE that is initially powered onis registered with a network through a cell selection process and the UEperforms cell reselection, if necessary.

Referring to FIG. 4, the UE selects Radio Access Technology (RAT) forcommunicating with a Public Land Mobile Network (PLMN), that is, anetwork from which the UE is provided with service (S410). Informationabout the PLMN and the RAT may be selected by the user of the UE, andinformation stored in a Universal Subscriber Identity Module (USIM) maybe used.

The UE selects a cell having the greatest value from cells whosemeasured BS and signal intensity or quality is greater than a specificvalue (S420). In this case, powered-on UE performs cell selection, whichmay be called initial cell selection. Cell selection procedure isdescribed in detail later. After the cell selection, the UE receivessystem information that is periodically transmitted by a BS. Thespecific value refers to a value defined in a system in order toguarantee quality for a physical signal in data transmission/reception.Accordingly, the value may be different depending on applied RAT.

If the UE needs to be registered with a network, the UE performs anetwork registration procedure (S430). The UE registers its owninformation (e.g., IMSI) with the network in order to receive service(e.g., paging) from the network. The UE does not register itsinformation with an accessing network whenever the UE selects a cell,but registers its information with a network if information (e.g.,Tracking Area Identity (TAI)) about the network received from systeminformation is different from information about the network which hasbeen known to the UE.

The UE performs cell reselection based on a service environment providedby a cell, the environment of the UE, etc. (S440). If a value of theintensity or quality of a signal measured from a BS that providesservice to the UE is lower than a value measured from a BS of aneighboring cell, the UE selects a cell from other cells that providebetter signal characteristics than the cell of the BS that the UE hasaccessed. This process is called cell reselection differently from theinitial cell selection of second process. Here, in order to prevent acell from being frequently reselected depending on a change of signalcharacteristics, a temporal restriction condition is imposed. The cellreselection procedure is described in detail later.

FIG. 5 is a flowchart illustrating a process of setting up an RRCconnection.

UE transmits an RRC connection request message, requesting an RRCconnection, to a network (S510). The network transmits an RRC connectionsetup message in response to the RRC connection request (S520). Afterreceiving the RRC connection setup message, the UE enters an RRCconnected mode.

The UE transmits an RRC connection setup complete message, used to checkthe successful completion of the RRC connection setup, to the network(S530).

FIG. 6 is a flowchart illustrating a process of reconfiguring an RRCconnection. An RRC connection reconfiguration is used to modify an RRCconnection. This is used to set up, modify/release an RB, performhandover, and set up, modify/release measurement.

A network transmits an RRC connection reconfiguration message formodifying an RRC connection to UE (S610). The UE transmits an RRCconnection reconfiguration complete message used to check the successfulcompletion of an RRC connection reconfiguration to the network inresponse to the RRC connection reconfiguration (S620).

A radio link failure is described below.

UE continues to perform measurement in order to maintain the quality ofa radio link to a serving cell from which service is received. The UEdetermines whether or not communication is impossible in a currentsituation due to the deterioration of quality of a radio link to aserving cell. If communication is almost impossible because the qualityof a serving cell is too low, the UE determines a current situation tobe a radio connection failure.

If a radio link failure is determined, the UE forgives maintainingcommunication with a current serving cell, selects a new cell through acell selection (or cell reselection) procedure, and attempts an RRCconnection reestablishment to the new cell.

FIG. 7 is an exemplary diagram showing a radio link failure. Anoperation related to a radio link failure may be described in twophases.

In the first phase, UE performs a normal operation and checks whether ornot there is a problem in a current communication link. If a problem isdetected, the UE declares a radio link problem and waits for therecovery of a radio link for a first standby time T1. If the radio linkis recovered before the first standby time elapses, the UE performs anormal operation again. If the radio link is not recovered until thefirst standby time expires, the UE declares a radio link failure andenters the second phase.

In the second phase, the UE waits for the recovery of the radio link fora second standby time T2. If the radio link is not recovered until thesecond standby time expires, the UE enters the RRC_idle state. Or, theUE may perform an RRC reestablishment procedure.

The RRC connection reestablishment procedure is a procedure ofreestablishing an RRC connection again in the RRC_connected state. Sincethe UE remains in the RRC_connected state, that is, since the UE doesnot enter the RRC_idle state, the UE does not initialize all its radioconfigurations (e.g., radio bearer configurations). Instead, the UEsuspends the use of all radio bearers other than an SRB0 when startingan RRC connection reconfiguration procedure. If an RRC connectionreconfiguration is successful, the UE resumes the use of suspended radiobearers.

FIG. 8 is a flowchart illustrating the success of a connectionreestablishment process.

UE selects a cell by performing cell selection. The UE receives systeminformation in order to receive basic parameters for cell access in theselected cell. Furthermore, the UE sends an RRC connectionreestablishment request message to a BS (S810).

If the selected cell is a cell having the context of the UE, that is, aprepared cell, the BS accepts the RRC connection reestablishment requestof the UE and transmits an RRC connection reestablishment message to theUE (S820). The UE transmits an RRC connection reestablishment completemessage to the BS, so the RRC connection reestablishment procedure canbe successful (S830).

FIG. 9 is a flowchart illustrating the failure of a connectionreestablishment process. UE transmits an RRC connection reestablishmentrequest message to a BS (S810). If a selected cell is not a preparedcell, the BS transmits an RRC connection reestablishment reject messageto the UE in response to the RRC connection reestablishment request(S815).

A radio link failure described with reference to FIG. 7 can be generateddue to the occurrence of a physical layer problem in an RRC_connectedstate, the occurrence of a random access problem, or an instructionrelated to retransmission on the RLC side.

When detecting a radio link failure or a handover failure, UE generatesradio link failure report information. The radio link failureinformation can include information about the identity of a PLMNcorresponding to the cell having the radio link failure, a recentmeasurement result (it may include RSRP and RSRQ) on a serving cell, ameasurement result on a neighboring cell, information about the locationof the UE, and the global cell identity of the cell having the radiolink failure. If UE generates radio link failure informationattributable to a radio link failure, the UE can include informationindicating that the radio link failure information has been generateddue to the radio link failure. If UE generates radio link failureinformation attributable to a handover failure, the UE can includeinformation indicating that the radio link failure information has beengenerated due to the handover failure.

When a radio link fails, UE can report the radio link failure to anetwork. The report of the radio link failure by the UE can be initiatedwhen the UE transmits a message that completes the establishment of anRRC connection with the network. In order to inform that a radio linkfailure to be reported is present, UE can include a radio linkfailure-available indicator in an RRC connection complete message (anRRC connection configuration confirm, RRC connection reconfigurationconfirm, or RRC connection reestablishment confirm message) and transmitthe RRC connection complete message.

The BS of a cell checks the radio link failure-available indicator. Ifit is checked that radio link failure information to be reported by UEis present, the BS sends a message that requests the UE to obtain UEinformation to the UE. In response thereto, the UE sends a UEinformation response message, including the radio link failureinformation, to the BS.

A procedure of UE selecting a cell is described in detail below.

When UE is powered on or the UE remains in a cell, the UE performsprocedures for receiving service by selecting/reselecting a cell havingsuitable quality.

UE in the RRC_idle state always needs to select a cell having suitablequality and to be prepared to receive service through this cell. Forexample, UE that is just powered on needs to select a cell havingsuitable quality in order to be registered with a network. When the UEin the RRC_connected state enters the RRC_idle state, the UE needs toselect a cell in which the UE will remain in the RRC_idle state. Aprocess in which the UE selects a cell that satisfies any condition inorder to remain in a service standby state, such as the RRC_idle state,as described above is called cell selection. An important point is thatthe UE needs to select a cell as rapidly as possible because cellselection is performed in the state in which the UE has not determined acell in which the UE will remain in the RRC_idle state. Accordingly, ifa cell provides the quality of a radio signal higher than a certainreference, although the cell is not a cell that provides the bestquality of a radio signal to the UE, the cell may be selected in thecell selection process of the UE.

A method and procedure of UE selecting a cell in 3GPP LTE are describedbelow with reference to 3GPP TS 36.304 V8.5.0 (2009-03) “User Equipment(UE) procedures in idle mode (Release 8)”.

When UE is initially powered on, the UE searches for an available PublicLand Mobile Network (PLMN) and selects a suitable PLMN from whichservice may be received. The PLMN is a network that is deployed ormanaged by a mobile network operator. Each mobile network operatormanages one or more PLMNs. Each PLMN can be identified by Mobile CountryCode (MCC) and Mobile Network Code (MNC). Information about the PLMN ofa cell is included in system information and broadcasted. UE attempts toregister a selected PLMN. If the registration is successful, theselected PLMN becomes a Registered PLMN (RPLMN). A network may signal aPLMN list to the UE. PLMNs included in the PLMN list may be consideredto be the same PLMNs as RPLMNs. UE registered with a network needs to bealways reachable by the network. If UE is in the ECM-CONNECTED state(identically an RRC_connected state), a network recognizes that the UEis provided with service. If the UE is in the ECM-IDLE state(identically the RRC_idle state), the situation of the UE is not validin an eNB, but is stored in an MME. In this case, only the MME isinformed of the location of the UE in the ECM-IDLE state as thegranularity of a list of Tracking Areas (TAs). A single TA is identifiedby a Tracking Area Identity (TAI) including a PLMN identity to which theTA belongs and Tracking Area Code (TAC) that uniquely represent a TAwithin a PLMN.

Next, the UE selects a cell having signal quality and characteristicsfrom which the UE can be provided with suitable service from cellsprovided by the selected PLMN.

A cell selection process is chiefly divided into two types.

First, as an initial cell selection process, in this process, UE doesnot have preliminary information about a radio channel. Accordingly, inorder to find a suitable cell, the UE searches all radio channels. TheUE searches each channel for the strongest cell. Next, the UE selects acorresponding cell only if it has only to find a suitable cell thatsatisfies a cell selection reference.

Next, the UE may select a cell using stored information or usinginformation broadcasted by a cell. Accordingly, cell selection may befaster than an initial cell selection process. The UE selects acorresponding cell if it has only to find a cell that satisfies a cellselection reference. If a suitable cell that satisfies the cellselection reference is not found through this process, the UE performsan initial cell selection process.

After UE selects any cell through a cell selection process, theintensity or quality of a signal between the UE and a BS may be changeddue to the mobility of the UE or a change of a radio environment.Accordingly, if the quality of a selected cell is deteriorated, the UEmay select another cell that provides better quality. If a cell isselected again as described above, the UE selects a cell that providesbetter signal quality than a currently selected cell. This process iscalled cell reselection. In general, the cell reselection process has abasic object to select a cell that provides the best quality to UE froma viewpoint of the quality of a radio signal.

In addition to the viewpoint of the quality of a radio signal, a networkcan determine priority by the frequency and inform UE of the determinedpriority. The UE which has received the priority preferentiallyconsiders this priority to be higher than a radio signal qualityreference in a cell reselection process.

There is a method of selecting or reselecting a cell based on the signalcharacteristics of a radio environment as described above. Upon cellreselection, in selecting a cell for reselection, the following cellreselection method may be used depending on the RAT and frequencycharacteristics of a cell.

-   -   Intra-frequency cell reselection: A reselected cell is a cell        having the same center-frequency and the same RAT as those used        in a cell on which the UE is currently being camped.    -   Inter-frequency cell reselection: A reselected cell is a cell        having the same RAT and a different center-frequency with        respect to those used in the cell on which the UE is currently        being camped.    -   Inter-RAT cell reselection: A reselected cell is a cell using a        different RAT from a RAT used in the cell on which the UE is        currently being camped.

The principle of a cell reselection process is as follows.

First, UE measures the quality of a serving cell and a neighboring cellfor cell reselection.

Second, cell reselection is performed based on a cell reselectionreference. The cell reselection reference has the followingcharacteristics in relation to the measurement of the serving cell andthe neighboring cell.

Intra-frequency cell reselection is basically based on ranking. Rankingis a task for defining a criterion value for cell reselection evaluationand ranking cells using the criterion value in order of a highercriterion value. A cell having the best criterion is commonly called thebest ranked cell. The cell criterion value is a value to which afrequency offset or a cell offset has been applied, if necessary, on thebasis of a value measured by UE for a corresponding cell.

Inter-frequency cell reselection is based on frequency priority providedby a network. UE attempts to camp on a frequency having the highestfrequency priority. A network may provide frequency priority that willbe in common applied by pieces of UEs within a cell through broadcastsignaling or may provide frequency-dedicated priority according to eachpiece of UE through UE-dedicated signaling.

For inter-frequency cell reselection, a network may provide UE with aparameter (e.g., a frequency-specific offset) used in cell reselectionby the frequency.

For intra-frequency cell reselection or inter-frequency cellreselection, a network may provide UE with a Neighboring Cell List (NCL)used in cell reselection. The NCL includes a cell-specific parameter(e.g., a cell-specific offset) used in cell reselection.

For intra-frequency or inter-frequency cell reselection, a network mayprovide UE with a cell reselection black list used in cell reselection.UE does not perform cell reselection on a cell that is included in theblack list

Ranking performed in a cell reselection evaluation process is describedbelow.

A ranking criterion used to assign priority to a cell is defined as inEquation 1.

R _(s) =Q _(meas,s) +Q _(hyst) , R _(n) =Q _(meas,n) +Q_(offset)  [Equation 1]

Here, R_(s) is a ranking criterion for a serving cell, R_(n) is aranking criterion for a neighboring cell, Q_(meas,s) is a quality valuemeasured by UE in relation to a serving cell, Q_(meas,n) is a qualityvalue measured by UE in relation to a neighboring cell, Q_(hyst) is ahysteresis value for ranking, and Q_(offset) is an offset between twocells.

In Intra-frequency, if UE receives an offset Q_(offsets,n) between aserving cell and a neighboring cell, Q_(offset)=Q_(offsets,n). If UEdoes not receive Q_(offsets,n), Q_(offset)=0.

In Inter-frequency, if UE receives an offset Q_(offsets,n) for acorresponding cell, Q_(offset)=Q_(offsets,n)+Q_(frequency). If UE doesnot receive Q_(offsets,n), Q_(offset)=Q_(frequency).

If the ranking criterion R_(s) of a serving cell and the rankingcriterion R_(n) of a neighboring cell are shifted in a similar state, UEmay alternately reselect two cells because ranking priority isfrequently changed as a result of the shift. Q_(hyst) is a parameterthat prevents UE from alternately reselecting two cells by giving ahysteresis in cell reselection.

UE measures R_(s) of a serving cell and R_(n) of a neighboring cellaccording to the above equation, considers a cell having the greatestranking criterion value to be the best ranked cell, and reselects thecell.

In accordance with the reference, it may be seen that the quality of acell functions as the most important reference in cell reselection. If areselected cell is not a suitable cell, UE excludes a correspondingfrequency or a corresponding cell from the subject of cell reselection.

Measurement and a measurement report are described below.

In a mobile communication system, the mobility support of UE isessential. Accordingly, UE consistently measures quality for a servingcell which now provides service and quality for a neighboring cell. UEreports a measurement result to a network on a suitable time, and anetwork provides the UE with the optimal mobility through handover, etc.Measurement for this purpose is called Radio Resource Management (RRM)Measurement.

In addition to the mobility support object, in order to provideinformation that may help a service provider to manage a network, UE mayperform measurement for a specific object set by the network and reporta measurement result thereof to the network. For example, UE may receivebroadcast information about a specific cell that has been determined bya network. UE may report a cell identity of the specific cell (this isalso called a global cell identity), location identity information(e.g., tracking area code) to which the specific cell belongs and/orother cell information (e.g., whether or not the specific cell is amember of a Closed Subscriber Group (CSG) cell) to a serving cell.

If UE in motion checks that the quality of a specific area is very poorthrough measurement, the UE may report location information and ameasurement result of cells having poor quality to a network. Thenetwork may attempt to optimize the network based on a report onmeasurement results from pieces of UE that help the operation of thenetwork.

In a mobile communication system whose frequency reuse factor is 1,mobility is chiefly performed between different cells in the samefrequency band. Accordingly, in order to well guarantee the mobility ofUE, the UE needs to be able to well measure the quality of neighboringcells having the same center frequency as a serving cell and informationabout the cells. As described above, measurement for a cell having thesame center frequency as a serving cell is called intra-frequencymeasurement. UE performs intra-frequency measurement and reports ameasurement result to a network on a suitable time so that the object ofa corresponding measurement result is achieved.

A mobile communication service provider may manage a network using aplurality of frequency bands. If a communication system provides servicethrough a plurality of frequency bands, in order to guarantee optimalmobility for UE, the UE needs to be able to well measure the quality ofneighboring cells having a different center frequency from a servingcell and information about the cells. As described above, measurementfor a cell having a different center frequency from a serving cell iscalled inter-frequency measurement. UE needs to be able to performinter-frequency measurement and report a measurement result to a networkon a suitable time.

If UE supports measurement for a heterogeneous network, measurement maybe performed on a cell of a heterogeneous network based on a BSconfiguration. Such measurement for a heterogeneous network is calledinter-Radio Access Technology (RAT) measurement. For example, RAT mayinclude a UMTS Terrestrial Radio Access Network (UTRAN) and a GSM EDGERadio Access Network (GERAN) that comply with the 3GPP standard and mayalso include a CDMA 2000 system that complies with the 3GPP2 standard.

FIG. 10 is a flowchart illustrating an existing method of performingmeasurement.

UE receives measurement configuration information from a BS (S1010). Amessage including the measurement configuration information is called ameasurement configuration message. The UE performs measurement based onthe measurement configuration information (S1020). The UE reports ameasurement result to the BS if the measurement result satisfies areport condition within the measurement configuration information(S1030). A message including the measurement result is called ameasurement report message.

The measurement configuration information may include the followinginformation.

(1) Measurement object information: information about the object onwhich measurement will be performed by UE. The measurement objectincludes at least one of an intra-frequency measurement object that isthe object of intra-cell measurement, an inter-frequency measurementobject that is the object of inter-cell measurement, and an inter-RATmeasurement object that is the object of inter-RAT measurement. Forexample, the intra-frequency measurement object may indicate aneighboring cell having the same frequency band as a serving cell, theinter-frequency measurement object may indicate a neighboring cellhaving a different frequency band from a serving cell, and the inter-RATmeasurement object may indicate a neighboring cell having different RATfrom a serving cell.

(2) Reporting configuration information: information about a reportcondition regarding when UE reports a measurement result and about areport type. The report condition may include information about an eventor period in which a report on a measurement result is triggered. Thereport type is information regarding that a measurement result will beconfigured according to what type.

(3) Measurement identity information: information about a measurementidentity, which makes UE determine to report what measurement objectaccording to what type when in association with a measurement object anda reporting configuration. The measurement identity information isincluded in a measurement report message, and it may indicate that ameasurement result is about what measurement object and that ameasurement report has been generated under what report condition.

(4) Quantity configuration information: information about a parameterfor configuring the filtering a measurement unit, a report unit and/or ameasurement result value.

(5) Measurement gap information: information about a measurement gap,that is, an interval which may be used by UE for only measurementwithout taking data transmission to a serving cell into consideration,because DL transmission or UL transmission has not been scheduled.

In order to perform a measurement procedure, UE has a measurement objectlist, a measurement report configuration list, and a measurementidentity list.

In 3GPP LTE, a BS may configure only one measurement object for onefrequency band regarding UE. In accordance with Paragraph 5.5.4 of 3GPPTS 36.331 V8.5.0 (2009-03) “Evolved Universal Terrestrial Radio Access(E-UTRA) Radio Resource Control (RRC); Protocol specification (Release8)”, events triggered by a measurement report, such as those in thefollowing table, are defined.

TABLE 1 Events Report Conditions Event A1 Serving becomes better thanthreshold Event A2 Serving becomes worse than threshold Event A3Neighbour becomes offset better than serving Event A4 Neighbour becomesbetter than serving Event A5 Serving becomes worse than threshold1 andneigbour becomes better than threshold2 Event B1 Inter RAT neighborbecomes better than threshold Event B2 Serving becomes worse thanthreshold1 and inter RAT neighbor becomes better than threshold2

If the measurement report of UE satisfies a set event, the UE transmitsa measurement report message to a BS.

FIG. 11 shows an example of a measurement configuration configured forUE.

First, a measurement identity 1(1101) connects an intra-frequencymeasurement object and a reporting configuration 1. UE performsintra-frequency measurement, and the reporting configuration 1 is usedto determine a reference and report type for a measurement resultreport.

Like the measurement identity 1(1101), a measurement identity 2(1102) isconnected to the intra-frequency measurement object, but the measurementidentity 2(1102) connects the intra-frequency measurement object and areporting configuration 2. UE performs intra-frequency measurement, andthe reporting configuration 2 is used to determine a reference and areport type for a measurement result report.

Based on the measurement identity 1(1101) and the measurement identity2(1102), UE transmits a measurement result of the intra-frequencymeasurement object if the measurement result satisfies any one of thereporting configuration 1 and the reporting configuration 2.

A measurement identity 3(1103) connects an inter-frequency measurementobject 1 and a reporting configuration 3. UE reports a measurementresult of the inter-frequency measurement object 1 if the measurementresult satisfies a report condition included in the reportingconfiguration 1.

A measurement identity 4(1104) connects an inter-frequency measurementobject 2 and the reporting configuration 2. UE reports a measurementresult of the inter-frequency measurement object 2 if the measurementresult satisfies a report condition included in the reportingconfiguration 2.

Meanwhile, a measurement object, a reporting configuration and/or ameasurement identity may be added, changed and/or deleted. This may beindicated when a BS transmits a new measurement configuration message toUE or transmits a measurement configuration change message to the UE.

FIG. 12 shows an example in which a measurement identity is deleted.When a measurement identity 2(1102) is deleted, measurement for ameasurement object associated with the measurement identity 2(1102) issuspended, and a measurement report is not also transmitted. Ameasurement object or a reporting configuration associated with thedeleted measurement identity may not be changed.

FIG. 13 shows an example in which a measurement object is deleted. Whenan inter-frequency measurement object 1 is deleted, UE also deletes anassociated measurement identity 3(1103). Measurement for theinter-frequency measurement object 1 is suspended, and a measurementreport is also not transmitted. However, a reporting configurationassociated with the deleted intra-frequency measurement object 1 may notbe changed or deleted.

When a reporting configuration is removed, UE also removes an associatedmeasurement identity. UE suspends measurement for a measurement objectassociated by the associated measurement identity. However, ameasurement object associated with the deleted reporting configurationmay not be changed or deleted.

A measurement report may include a measurement identity, the measuredquality of a serving cell, and a measurement result of a neighboringcell. The measurement identity identifies a measurement object whosemeasurement report has been triggered. The measurement result of theneighboring cell may include a cell identity and measured quality of theneighboring cell. The measured quality may include at least one ofReference Signal Received Power (RSRP) and Reference Signal ReceivedQuality (RSRQ).

A Minimization Drive Test (MDT) is described below.

An MDT enables UE to perform measurement and report a result thereofinstead of a drive test in which conventional service providers measurethe quality of cells using vehicles for cell coverage optimization.Coverage varies depending on the location of a BS, the deployment ofperipheral buildings, and a use environment of a user. Accordingly, aservice provider needs to periodically perform a drive test, whichconsumes lots of costs and resources. In order to overcome thedisadvantages, there is proposed an MDT in which a service providermeasures coverage using UE.

A service provider may write a coverage map, indicating whether or notservice is possible over the entire area to which service is provided bya service provider and a distribution of QoS, by synthesizing MDTmeasurement values received from several pieces of UE and use thewritten coverage map in network operations and optimization. Forexample, when a report on a coverage problem for a specific area isreceived from UE, a service provider may enlarge the coverage of acorresponding area cell by increasing the transmission power of a BSthat provides service to the corresponding area. The time and costnecessary for network optimization can be minimized through such amethod.

An MDT has been produced based on the framework of a tracking function,that is, one of the tools of an operator for Operation, Administration,and Maintenance (OAM). The tracking function provides an operator withthe ability to perform tracking and to log the behaviors of UE and thuscan enable the operator to determine the major cause of a functionfailure on the UE side. Traced data is collected over a network, whichis called a Trace Collection Entity (TCE). An operator uses datacollected in a TCE for analysis and evaluation. A tracking function usedfor an MDT includes signaling based on a tracking function andmanagement based on tracking function. Signaling based on a trackingfunction is used to activate an MDT task toward specific UE, whereasmanagement based on tracking functions is used to activate an MDT taskwithout being limited to specific UE.

An MDT may be divided into two types: a logged MDT and an immediate MDTdepending on whether UE reports measured and stored log data in anon-real time or in real time. The logged MDT is a method of UEperforming MDT measurement, logging corresponding data, and sending thelogged data to a network. In contrast, the immediate MDT is a method ofUE performing MDT measurement and immediately sending corresponding datato a network. In accordance with the logged MDT, UE performs MDTmeasurement in the RRC_idle state. In accordance with the immediate MDT,UE performs MDT measurement in the RRC_connected state.

FIG. 14 is a flowchart illustrating a method of performing a logged MDT.

Referring to FIG. 14, UE receives a logged measurement configuration(S1410). The logged measurement configuration may be included in an RRCmessage and transmitted through a downlink control channel. The loggedmeasurement configuration may include at least one of a TCE ID,information about a reference time that is a basis for logging, loggingduration, a logging interval, and information about an areaconfiguration. The logging interval indicates an interval in which ameasurement result is stored. The logging duration indicates durationfor which UE performs a logged MDT. The reference time indicates areference time for duration for which a logged MDT is performed. Thearea configuration indicates an area that has been requested to belogged by UE.

Meanwhile, UE initiates a validity timer when a logged measurementconfiguration is received. The validity timer means the lifetime of thelogged measurement configuration, which may be specified by informationabout logging duration. The duration of the validity timer may indicatethe validity of measurement results owned by UE as well as the validlifetime of a logged measurement configuration.

A procedure in which UE performs a logged measurement configuration anda corresponding overall procedure is performed as described above iscalled a configuration phase.

When the UE enters the RRC_idle state (S1421), the UE logs themeasurement result while the validity timer is driven (S1422). Ameasurement result value may include RSRP, RSRQ, Received Signal CodePower (RSCP), Ec/No, etc. Information on which a measurement result hasbeen logged is called logged measurement. A temporal interval in whichUE logs a measurement result one or more times is called a loggingphase.

The execution of a logged MDT based on a logged measurementconfiguration by UE may vary depending on the location of the UE.

FIG. 15 is a diagram showing an example of a logged MDT according to alogging area.

A network may configure a logging area that is an area in which UE hasto log. The logging area may be represented as a cell list or a trackingarea/location area list. If a logging area is configured in UE, the UEsuspends logging when the UE gets out of the logging area.

Referring to FIG. 15, a first area 1510 and a third area 1530 are areasconfigured as logging areas, and a second area 1520 is an area in whichlogging is not permitted. UE performs logging in the first area 1510,but does not perform logging in the second area 1520. UE performslogging again when the UE moves from the second area 1520 to the thirdarea 1530.

FIG. 16 is a diagram showing an example of a logged MDT according to achange of RAT.

UE performs logging only when the UE camps on RAT from which a loggedmeasurement configuration has been received and suspends logging inanother RAT. However, the UE may log cell information about other RATsin addition to camp-on RAT.

A first area 1610 and a third area 1630 are E-UTRAN areas, and a secondarea 1620 is a UTRAN area. A logged measurement configuration isreceived from the E-UTRAN. When UE enters the second area 1620, the UEdoes not perform MDT measurement.

Referring back to FIG. 14, the UE enters the RRC_connected state(S1431). If logged measurement to be reported is present, the UE informsan eNB that the logged measurement to be reported is present (S1432).The UE may inform the eNB that the logged measurement is present when anRRC connection is established, an RRC connection is reestablished, or anRRC connection is reconfigured. Furthermore, if the UE performshandover, the UE may inform a handover target cell of a presence of thelogged measurement. Informing, by the UE, the eNB that the loggedmeasurement is present may include including a loggedmeasurement-available indicator, that is, indication informationinforming that the logged measurement is present, in an RRC messagetransmitted from the UE to the eNB and sending the RRC message. The RRCmessage may be an RRC connection configuration complete message, an RRCconnection reestablishment complete message, an RRC reconfigurationcomplete message, or a handover complete message.

When the eNB receives a signal informing that the logged measurement ispresent from the UE, the eNB request the UE to report logged measurement(S1433). Requesting the report on the logged measurement may includeincluding a logged measurement report request parameter regardinginformation indicative of the request in an RRC message and sending theRRC message. The RRC message may be a UE information request message.

When the UE receives the request to report the logged measurement fromthe eNB, the UE reports the logged measurement to the eNB (S1434).Reporting the logged measurement to the eNB may include including thelogged measurement report, including pieces of logged measurement, in anRRC message and sending the RRC message to the eNB. The RRC message maybe a UE information report message. In reporting the logged measurement,the UE may report all or some of pieces of logged measurement owned bythe UE on a report time point to the eNB. If the UE reports some ofpieces of logged measurement, the reported pieces of logged measurementmay be discarded.

A phase of a process in which the UE informs the eNB that the loggedmeasurement is present, receives a request to report the loggedmeasurement from the eNB, and reports the logged measurement isperformed as described above is called a report phase.

A radio environment is chiefly measured by the UE while a logged MDT isperformed. MDT measurement may include a cell identity and the signalquality and/or signal intensity of the cell. MDT measurement may includea measurement time and a measurement place. The following tableillustrates contents logged by UE.

TABLE 2 Parameter (set) Contents Serving Global cell identity of aserving cell cell identity Measurement result of Measured RSRP ofserving cell serving cell Measured RSRQ of serving cell Measurementresult of Cell identities of measured E-UTRA cells, neighbor cellMeasurement results of UTRA cells Cell identities of measured UTRAcells, Measurement results of UTRA cells Cell identities of measuredGERAN cells, Measurement results of GERAN cells Cell identities ofmeasured CDMA2000 cells, Measurement results of CDMA200 cells Time stampTime of logging measurement result, calculated (current time-referencetime), calculated in seconds Location information Detailed locationinformation of logging time point

Information logged at different logging time points can be classifiedand stored according to different log entries.

FIG. 17 is a diagram showing an example of logged measurement.

Logged measurement includes one or more log entries.

The log entry includes a logging location, a logging time, a servingcell identity, a serving cell measurement result, and a neighboring cellmeasurement result.

The logging location indicates the location where UE has performedmeasurement. The logging time indicates the time when UE has performedmeasurement. Pieces of information logged at different logging times arestored in different log entries.

The serving cell identity may include a cell identity in the layer 3,which is called a Global Cell Identity (GCI). The GCI is a set of aPhysical Cell Identity (PCI) and a PLMN identity.

Meanwhile, UE may perform logging by analyzing criteria related to theperformance of UE in addition to a radio environment. For example, thecriteria related to the performance of UE may include a throughput, anerroneous transmission/reception rate, etc.

Referring back to FIG. 14, the aforementioned logging phase and reportphase may be present in plural times for logging duration (S1441,S1442).

The eNB may record/store the logged measurement on/in a TCE when thelogged measurement is reported.

If the UE has logged measurement that has not been reported after thevalidity timer expires, that is, after the logging duration elapses, theUE performs a procedure for reporting the logged measurement to the eNB.A phase in which the overall procedure for the procedure is called apost-reporting phase.

When the logging duration expires, the UE discards the loggedmeasurement configuration and initiates a conservation timer. After thelogging duration is terminated, the UE suspends MDT measurement.However, the already logged measurement remains intact without beingdiscarded. The conservation timer indicates the lifetime of theremaining logged measurement.

When the UE enters the RRC_connected state (S1451) before theconservation timer expires, the UE may report logged measurement to theeNB. In this case, the aforementioned procedure for a logged measurementreport may be performed (S1452, S1453, S1454). When the conservationtimer expires, the remaining logged measurement may be discarded. Whenthe logged measurement is reported, the eNB may record/store the loggedmeasurement on/in the TCE.

The conservation timer may be fixed to a predetermined value in the UEand may be previously set in the UE. For example, a value of theconservation timer may be 48 hours. Or, a value of the conservationtimer may be included in the logged measurement configuration andtransferred to the UE or may be included in a different RRC message andtransferred to the UE.

Meanwhile, when a new logged measurement configuration is transferred tothe UE, the UE may update an existing logged measurement configurationinto the newly obtained logged measurement configuration. In this case,the validity timer can be started again from the time when the loggedmeasurement configuration is newly received. Furthermore, loggedmeasurement based on the previous logged measurement configuration maybe discarded.

FIG. 18 is a diagram showing an example of an immediate MDT. Theimmediate MDT is based on a Radio Resource Management (RRM) measurementand report mechanism. In addition, information related to the locationupon a measurement report is added and reported to an eNB.

Referring to FIG. 18, UE receives an RRC connection reconfigurationmessage (S1810) and transmits an RRC connection reconfiguration completemessage (S1820). Thus, the UE enters the RRC_connected state. The UE mayreceive a measurement configuration by receiving the RRC connectionreconfiguration message. In the example of FIG. 18, the measurementconfiguration has been illustrated as being received through the RRCconnection reconfiguration message, but the measurement configurationmay be included in a different RRC message and transmitted.

The UE performs measurement and evaluation in the RRC_connected state(S1831) and reports a measurement result to the eNB (S1832). In theimmediate MDT, the measurement result may provide precise locationinformation, as possible, as in the example of location informationprovided by a Global Navigation Satellite System (GNSS). For locationmeasurement, such as an RF fingerprint, the measurement result mayprovide measurement information about a neighboring cell, which may beused to determine the location of UE.

From FIG. 18, it may be seen that even after the executed measurementand evaluation (S1831) and the report (S1832), the UE reports ameasurement result (S1843) to the eNB right after performing measurementand evaluation (S1842). This is the biggest difference between thelogged MDT and the immediate MDT.

In-Device Coexistence (IDC) is described below.

In order for a user to access various networks anywhere and at any time,UE can be equipped with a Global Navigation Satellite System (GNSS)receiver in addition to a transceiver for wireless communicationsystems, such as LTE, Wi-Fi, and Bluetooth (BT). For example, there maybe UE on which LTE and BT modules are mounted in order to receive VoIPservice and multimedia service using BT equipment, UE on which LTE andWi-Fi modules are mounted for a traffic distribution, UE on which GNSSand LTE modules are mounted in order to additionally receive locationinformation.

In this case, since several transceivers are closely located within theUE, the intensity of power transmitted by one transmitter can be greaterthan the reception power of another receiver. Interference between twotransceivers (IDC interference) can be prevented by placing a gap infilter technology or a use frequency. However, if several wirelesscommunication modules operate in neighboring frequencies within a pieceof UE, interference cannot be sufficiently removed by current filtertechnology. In the future, for the coexistence of transceivers for aplurality of wireless communication modules within UE, the above problemneeds to be solved. FIG. 19 shows a situation in which mutualinterference can be generated in an IDC environment in which LTE, GPS,and BT/Wi-Fi coexist within a piece of UE.

IDC interference avoidance is basically classified into three types ofmodes depending on whether coordination with another communicationmodule coexisting with an LTE module is present or not and whethercoordination with an LTE module and a BS is present or not in order tosolve IDC interference. The first is a mode in which no coordination ispresent for IDC interference avoidance between coexistence communicationmodules and LTE and a network. In this case, the deterioration ofservice quality attributable to IDC interference may not be properlyprocessed because the LTE module is unaware of information about anothercommunication module that coexists along with the LTE module. The secondmode is a case where coordination between coexistence communicationmodules is present within UE. In this mode, an on/off state, a traffictransmission state, etc. for a counterpart module can be aware betweencoexisting modules. In this mode, however, there is no coordinationbetween the UE and a network. The final mode is a mode in which there isno coordination within UE between the UE and a network as well ascoordination between coexistence modules. In this mode, a coexistingmodule can be aware of an on/off state, a traffic transmission state,etc. for a counterpart module, and UE informs a network of an IDCinterference state. Accordingly, the network makes a determination andtakes measures for avoiding IDC interference.

As described above, an LTE module can measure IDC interference throughinter/intra frequency measurement as well as coordination with othermodules within UE.

Interference can be IDC interference generated because differentcommunication modules coexist and operate within a piece of UE, and theIDC interference can be generated in the following coexistencesituation.

Interference is generated in a situation in which LTE and Wi-Fi coexist.

Interference is generated in a situation in which LTE and BT coexist.

Interference is generated in a situation in which LTE and GNSS coexist.

Communication modules influence mutual interference because they operateneighboring frequencies as follows in terms of the frequency.

LTE TDD can operate in a Band 40 (2300 MHz to 2400 MHz), and Wi-Fi andBT can operate in an unlicensed band (2400 MHz to 2483.5 MHz). In thiscase, the transmission of LTE can give interference with Wi-Fi and BT,and the transmission of Wi-Fi or BT can give interference with thereception of LTE.

In LTE FDD, uplink transmission can be performed in a Band 7 (2500 MHzto 2700 MHz), and Wi-Fi and Bluetooth can operate in an unlicensed band(2400 MHz to 2483.5 MHz). In this case, the uplink transmission of LTEcan give interference with the reception of Wi-Fi or Bluetooth.

In LTE FDD, uplink transmission can be performed in a Band 13 (UL: 777to 787 MHz, DL: 746 to 756 MHz) or Band 14 (UL: 788 to 798 MHz, DL: 758to 768 MHz), and in GPS radio, reception can be performed in 1575.42MHz. In this case, the uplink transmission of LTE can give interferencewith the reception of a GPS.

In current 3GPP, three directions are being discussed in order to solveIDC interference. The first is a method in which a communication modulethat provides interference or a communication module that is subject tointerference changes its frequency (Frequency Division Multiplexing(FDM)). The second is a method in which a communication module using acoexisting frequency splits and uses the time (Time DivisionMultiplexing (TDM)). The last is a method in which an LTE module reducesinterference that affects a coexisting module by controlling itstransmission power (LTE Power control (PC)). A detailed method andprocedure are being discussed in 3GPP.

Since IDC interference is interference generated within UE, an LTE BS isunaware that the IDC interference generated within the UE is in whatsituation. If a network can obtain information about an IDC interferencesituation generated within UE, the network may provide the UE with meansthat enables the UE to effectively avoid the IDC interference based onthe information. There is proposed a method in which UE logs informationabout IDC interference generated within the UE and reporting theinformation to a network. Another communication module that may generateinterference with a module which supports wireless communication, suchas LTE, is hereinafter called an in-device. Interference generated by anin-device and/or interference caused by an in-device is hereinaftercalled IDC interference.

FIG. 20 is a flowchart illustrating a method for logging IDCinterference information and reporting the log in accordance with anembodiment of the present invention. FIG. 20 illustrates a method forlogging IDC interference information and reporting a corresponding logto a network when a specific condition is satisfied.

Referring to FIG. 20, UE receives an IDC interference measurementconfiguration from a network (S2010). The IDC interference measurementconfiguration includes a logging start indicator that instructs the UEto start IDC interference measurement.

The UE measures IDC interference in order to log IDC interferenceinformation (S2020). The IDC interference information logged by the UEmay include information about an IDC interference situation and/or IDCoperation information related to the operation of an in-device.

The information about an IDC interference situation may include IDCinterference caused by an in-device and IDC interference affecting thein-device. Accordingly, the UE can measure IDC interference caused bythe in-device and IDC interference affecting the in-device.

In order to log the information about an IDC interference situation, theUE measures IDC interference caused by an in-device. The measurement ofthe IDC interference attributable to the in-device by the UE may beperformed as follows.

A measurement mode 1: the UE calculates a measurement result bymeasuring an LTE subframe including interference due to an in-device.

A measurement mode 2: the UE calculates a measurement result bymeasuring the remaining LTE subframes other than the LTE subframeincluding interference due to an in-device.

A measurement mode 3: the measurement result calculated using themeasurement mode 1 and the measurement result calculated using themeasurement mode 2 are calculated.

A measurement mode 4: a difference between the measurement resultcalculated using the measurement mode 1 and the measurement resultcalculated using the measurement mode 2 is calculated.

The UE may be configured to perform measurement using a predeterminedand specific measurement mode of the measurement modes. Or, a networkmay indicate a measurement mode to be used when the UE measures IDCinterference attributable to an in-device. Information indicative of themeasurement mode may be included in an IDC interference measurementconfiguration and transmitted.

Additionally, the UE may have a time interval in which interference willbe measured through a specific measurement mode configured by a networkand may measure interference through the specific measurement mode inthe corresponding time interval. In this case, information about thetime interval in which the specific measurement mode is used may beincluded in an IDC interference measurement configuration andtransmitted.

The UE can be aware of a subframe including interference and a subframenot including interference prior to measurement. The UE can obtaininformation regarding how the transmission and reception operations ofradio signals are performed by an in-device and how the transmission andreception operations of radio signals are scheduled because an LTEmodule and an in-device coexist within the UE. Accordingly, the UE canbe aware that IDC interference affecting an LTE module due to thetransmission and reception of radio signals of the in-device is presentin what subframe. Accordingly, a subframe corresponding to timing atwhich IDC interference may be generated can be assumed to be a subframeincluding interference, and the remaining subframes may be assumed to besubframes not including interference. Meanwhile, the UE may use thefollowing conditions in determining that IDC interference attributableto an in-device can be generated in a specific subframe.

A condition 1: the transmission power of an in-device exceeds athreshold

A condition 2: the transmission of an in-device is generated at specifictiming (e.g., when in-device transmission is generated at subframetiming at which a reference signal for measuring the quality of an LTEserving cell is generated)

A condition 3: when frequency in which the condition 2 is generated is aspecific threshold or higher (e.g., when a ratio of in-devicetransmission during subframe timing used for LTE serving cellmeasurement is a specific threshold or higher during a specific timeinterval)

A condition 4: when a decoding failure rate of an LTE reception signalexceeds a specific threshold

A condition 5: one combination of at least one among the condition 1 tothe condition 4, and when conditions used in the combination aresatisfied at the same time (e.g., when both the condition 1 and thecondition 2 are satisfied. That is, in-device transmission is generatedat subframe timing at which a reference signal for measuring LTE servingcell quality is generated, and in-device transmission power exceeds thethreshold)

Which one of the conditions will be used may be configured in the UE inadvance. The UE can be aware of a subframe in which IDC interferenceattributable to an in-device may be present according to a predeterminedcondition.

Or, a network may indicate a condition that becomes a base on which theUE determines whether or not IDC interference attributable to anin-device can be present. In this case, information indicative of aspecific condition may be included in an IDC interference measurementconfiguration and transmitted.

In order to log information about an IDC interference situation, the UEmeasures IDC interference that affects an in-device due to LTE. The UEmay measure IDC interference that affects the in-device as follows.

A measurement mode 1: the UE calculates a measurement result bymeasuring an LTE subframe including interference that affects anin-device.

A measurement mode 2: the UE calculates a measurement result bymeasuring LTE subframes other than the LTE subframe includinginterference that affects an in-device.

A measurement mode 3: the UE calculates the measurement resultcalculated through the measurement method 1 and the measurement resultcalculated through the measurement method 2.

A measurement mode 4: the UE calculates a difference between themeasurement result calculated through the measurement method 1 and themeasurement result calculated through the measurement method 2.

The UE may be configured to perform measurement according to apredetermined and specific measurement mode of the measurement modes.Or, a network may indicate a measurement mode to be used when the UEmeasures IDC interference that affects an in-device. Informationindicative of the measurement mode may be included in an IDCinterference measurement configuration and transmitted.

Additionally, the UE may have a time interval in which interference willbe measured through a specific measurement mode and a time pattern usedin interference measurement configured by a network and measureinterference through the specific measurement mode in the correspondingtime interval or time pattern. In this case, information about the timeinterval in which the specific measurement mode is used may be includedin an IDC interference measurement configuration and transmitted.

The UE may be aware of a subframe including interference and a subframenot including interference prior to measurement. The UE may be aware ofscheduling information about when a radio signal will be transmittedthrough an LTE module. Accordingly, the UE can be aware of a subframehaving a possibility that IDC interference attributable to thetransmission and reception of radio signals of the LTE module willaffect an in-device. Accordingly, a subframe in which IDC interferencecan be generated may be assumed to be a subframe including interference,and the remaining subframes may be assumed to be subframes not includinginterference. The UE may use the following conditions in determiningwhether IDC interference affecting an in-device is present or not. TheUE may use the following conditions in determining that IDC interferenceaffecting an in-device may be generated in a specific subframe.

A condition 1: LTE transmission power exceeds a threshold

A condition 2: the transmission of an UE LTE device is generated atimportant specific timing in order to maintain an in-device operation(e.g., when UE LTE transmission is generated at channel timing for thesynchronization of an in-device)

A condition 3: when frequency that the condition 2 is generated is athreshold or higher (e.g., when a timing ratio in which UE LTEtransmission is generated, from channel timing for the synchronizationof an in-device, is a threshold or higher during a specific timeinterval)

A condition 4: a decoding failure rate of an in-device reception signalexceeds a threshold

A condition 5: a combination of at least one among the condition 1 tothe condition 4, and when conditions used in the combination aresatisfied at the same time.

Which one of the conditions will be used may be configured in the UE inadvance. The UE can be aware of a subframe in which IDC interferenceaffecting an in-device may be present according to a predeterminedcondition.

Or, a network can indicate a condition that becomes a base on which theUE determines whether or not IDC interference affecting an in-device canbe present. In this case, information indicative of a specific conditioncan be included in an IDC interference measurement configuration andtransmitted.

The UE logs IDC interference information (S2030).

The UE may log IDC interference situation information which includes ameasurement result of IDC interference due to an in-device and/or ameasurement result of IDC interference that affects the in-device.

When logging the IDC interference measurement results, timing used inmeasurement for obtaining the measurement results may be logged. Thetiming may be the timing of an LTE subframe unit. Timing information maybe used for a BS to check a specific LTE subframe or specific LTEsubframe pattern having high IDC interference based on the timinginformation. Or, the timing information may be used as referenceinformation for checking a specific LTE subframe or specific LTEsubframe pattern having low IDC interference.

In logging IDC interference information, the UE may log IDC operationinformation related to the operation of an in-device. The IDC operationinformation may indicate an event related to the operation of anin-device, and the event can include the following events.

An event 1a: an in-device is enabled. According to embodiments, theenabled state of the in-device may mean that a connection with theobject to and from which the in-device will transmit and receiveinformation is established or a state in which a preparation for thetransmission and reception of information to and from the object hasbeen completed. The enabled state of the in-device can mean a state inwhich the in-device is turned on.

An event 1b: an in-device is disabled.

An event 2a: the transmission of an in-device is started

An event 2b: the transmission of an in-device is suspended

An event 3a: the reception of an in-device is started

An event 3b: the reception of an in-device is suspended

The UE may log the IDC interference situation information and the IDCinterference operation information at the same time. Or, the UE may logthe IDC interference situation information and the IDC interferenceoperation information independently.

Information indicating that logged specific IDC interference informationis about what in-device may be included. To this end, the UE may includean identity indicative of the in-device in the IDC interferenceinformation.

The UE may log information about the location of the UE at a point oftime at which IDC interference information is logged by logging thecorresponding IDC interference information.

The UE may log information indicative of a point of time at which IDCinterference information is logged by logging the corresponding IDCinterference information.

The UE reports the log to a network (S2040).

The UE may log the IDC interference information for a specific periodand report the log to the network at a specific point of time, in thesame manner that the UE reports logged measurement according to a loggedMDT. In this case, when a log report request is received from network,the UE may report the log to the network in response to the log reportrequest.

A period in which the UE logs the IDC interference information may beset. The logging period may be specified to a specific number ofsubframes or may be specified to a specific number of radio frames or aspecific time interval. For example, if the logging period is given as40 subframes, the UE may obtain and log IDC interference informationabout each of interference subframes within the 40-subframe interval.After the 40-subframe interval elapses, the UE may report a log to thenetwork. Information about the logging period may be included in an IDCinterference measurement configuration.

The UE may immediately report a log to the network when loggingindividual IDC interference information in the same manner that the UEreports a measurement result according to an immediate MDT to a network.

The UE may include information indicating that an in-device log isrelated to what in-device, that is, an identity indicative of a relatedspecific in-device.

Meanwhile, when the UE reports the log to the network, the UE maycontrol and/or delay report timing in order to use an LTE subframehaving small interference from an in-device and/or in order to report alog at timing at which interference affecting the in-device isgenerated.

In the IDC interference information logging and log reporting method ofFIG. 20, an in-device is a device placed such that it coexists with thesame physical device as an LTE transmission and reception device, andthe in-device means a device that causes IDC interference attributableto the in-device due to the distance close to the LTE transmission andreception device and/or a device that gives IDC interference to thein-device.

An in-device may be a BT-supporting device based on IEEE 802.15.1.

An in-device may be a Zigbee-supporting device based on IEEE 802.15.4.

An in-device may be a Wi-Fi-supporting device based on IEEE 802.11.

An in-device may be a WiMax-supporting device based on IEEE 802.16.

FIG. 21 is a diagram showing an example of a method of logginginterference information and reporting a log in an IDC environment towhich an embodiment of the present invention has been applied.

Referring to FIG. 21, UE receives an IDC interference measurementconfiguration from a network (S2110). The IDC interference measurementconfiguration may include the information described with reference toFIG. 20. In this example, it is assumed that the interferencemeasurement configuration includes information indicating the loggingperiod of the UE using a 10-subframe interval, that is, one radio frameinterval.

The UE performs IDC interference measurement and logs IDC interferenceinformation within a radio frame A interval (S2120). The UE performs IDCinterference measurement on subframes A-1 and A-7 in which IDCinterference attributable to an in-device can be generated and thesubframes A-7 and A-8 in which IDC interference affecting the in-devicemay be generated. Furthermore, the UE performs IDC interferencemeasurement on each of the subframes and logs IDC interferenceinformation about each of the subframes. The logged IDC interferenceinformation may include the pieces of information described withreference to FIG. 20.

The UE reports the measurement performed within the radio frame Ainterval and a first log according to a logging procedure to the network(S2130). In this figure, the report has been illustrated as beingperformed to the network immediately after a lapse of the radio frame Ainterval, but timing for the log report may be controlled and/ordelayed. Furthermore, to report the log to the network can be performedin response to a log request from the network.

The UE performs IDC interference measurement and logs IDC interferenceinformation within a radio frame B interval (S2130). The UE performs IDCinterference measurement on subframes B-3, B-8, and B-9 in which IDCinterference attributable to an in-device and/or IDC interferenceaffecting the in-device can be generated. Furthermore, after performingIDC interference measurement on each of the subframes, the UE logs IDCinterference information. The logged IDC interference informationincludes the pieces of information described with reference to FIG. 20.

The UE reports the measurement performed within the radio frame Binterval and a second log according to a logging procedure to thenetwork (S2140). In this figure, the report has been illustrated asbeing performed to the network immediately after a lapse of the radioframe B interval, but timing for the log report may be controlled and/ordelayed. Furthermore, to report the log to the network may be performedin response to a log request from the network.

FIG. 21 shows an example of an IDC interference information logging andlog reporting method based on a non-real-time log report. Unlike in FIG.21, in the case of a real-time log report, a log may be reported to thenetwork right after IDC interference is measured and IDC interferenceinformation is logged in each subframe.

In accordance with the present invention, UE can effectively log anin-device interference situation and operation situation and report thelog to a network. The network can perform a configuration for minimizingin-device interference for the UE in the UE because it can obtaininformation about the pattern of a subframe in which interference can begenerated by analyzing the log. Accordingly, service efficiency andradio resources efficiency of IDC UE can be improved.

FIG. 22 is a block diagram showing a radio device in which an embodimentof the present invention can be implemented. The device can implementthe operation of UE in the embodiments of FIGS. 19 to 21.

The radio device 2200 includes a first processor 2211, a secondprocessor 2212, memory 2220, a first Radio Frequency (RF) unit 2231, anda second RF unit 2232.

The first RF unit 2231 is configured to transmit and receive the radiosignals of an LTE wireless communication system. The first processor2211 is configured to perform LTE wireless communication whilefunctionally operating in conjunction with the first RF unit.

The second RF unit 2231 is configured to transmit and receive the radiosignals of wireless communication systems, such as Wi-Fi, WiMAX, Zigbee,and BT. The second processor 2212 operates while functionally operatingin conjunction with the second RF unit, and it is configured to performthe wireless communication of a wireless communication systemcorresponding to the second RF unit.

The first processor 2211 performs the proposed functions, processesand/or methods. The first processor 2211 measures IDC interference for asubframe in which in-device interference can be generated due to thesecond RF unit 2232 and the second processor 2212. The first processor2211 can log IDC interference information in the memory 2220. The firstprocessor 2211 is configured to report the log to a network. Theembodiments of FIGS. 19 to 21 can be implemented by the first processor2211 and the memory 2220.

The processor may include Application-Specific Integrated Circuits(ASICs), other chipsets, logic circuits, and/or data processors. Thememory may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit may include a baseband circuit for processing radio signals.When the above-described embodiment is implemented in software, theabove-described scheme may be implemented into a module (process orfunction) configured to perform the above function. The module may bestored in the memory and executed by the processor. The memory may beplaced inside or outside the processor and connected to the processorusing a variety of well-known means.

In the above exemplary system, although the methods have been describedbased on the flowcharts in the form of a series of steps or blocks, thepresent invention is not limited to the sequence of the steps, and someof the steps may be performed in a different order from that of othersteps or may be performed simultaneous to other steps. Furthermore,those skilled in the art will understand that the steps shown in theflowchart are not exclusive and the steps may include additional stepsor that one or more steps in the flowchart may be deleted withoutaffecting the scope of the present invention.

1. A wireless apparatus comprising: a first Radio Frequency (RF) unittransmitting and receiving radio signals according to a first wirelesscommunication system; a second RF unit transmitting and receiving radiosignals according to a second wireless communication system; and aprocessor operably coupled to the first RF unit, wherein the processoris configured to: receive an In-Device Coexistence (IDC) interferencemeasurement configuration from a network, wherein the IDC interferencemeasurement configuration comprises information instructing that alogging of IDC interference information be started, perform first IDCinterference measurement on a first subframe, log first IDC interferenceinformation comprising a first IDC interference measurement result,perform second IDC interference measurement on a second subframe, logsecond IDC interference information comprising a second IDC interferencemeasurement result, and report the first IDC interference informationand the second IDC interference information to the network.
 2. Thewireless apparatus of claim 1, wherein the IDC interference measurementconfiguration further comprises information indicative of a log reporttype.
 3. The wireless apparatus of claim 2, wherein if the log reporttype indicates a non-real-time log report type, the first IDCinterference information and the second IDC interference information aretogether reported to the network after a specific point of time.
 4. Thewireless apparatus of claim 3, wherein the IDC interference measurementconfiguration further comprises logging interval indication informationindicative of the specific point of time.
 5. The wireless apparatus ofclaim 4, wherein the reporting the first IDC interference informationand the second IDC interference information to the network comprises:receiving a log report request from the network, and sending the firstIDC interference information and the second IDC interference informationto the network in response to the log report request.
 6. The wirelessapparatus of claim 2, wherein if the log report type indicates areal-time log report type, the first IDC interference information andthe second IDC interference information are individually logged andindividually reported to the network.
 7. The wireless apparatus of claim1, wherein the first IDC interference information further comprisesinformation about timing of the first IDC interference measurement. 8.The wireless apparatus of claim 7, wherein the information about thetiming of the first IDC interference measurement is timing informationof a subframe unit.
 9. The wireless apparatus of claim 1, wherein thefirst RF unit and the processor support Long Term Evolution (LTE)wireless communication.
 10. The wireless apparatus of claim 2, whereinthe second RF unit supports at least one of WLAN (Wi-Fi), WiMAX, Zigbee,and Bluetooth wireless communications.
 11. A method for logging andreporting In-Device Coexistence (IDC) interference information,performed by IDC UE, in a wireless communication system, comprising:receiving an In-Device Coexistence (IDC) interference measurementconfiguration from a network, the IDC interference measurementconfiguration comprising information instructing that a logging of IDCinterference information be started, performing first IDC interferencemeasurement on a first subframe, logging first IDC interferenceinformation comprising a first IDC interference measurement result,performing second IDC interference measurement on a second subframe,logging second IDC interference information comprising a second IDCinterference measurement result, and reporting the first IDCinterference information and the second IDC interference information tothe network.
 12. The method of claim 11, wherein the IDC interferencemeasurement configuration further comprises information indicative of alog report type.
 13. The method of claim 12, wherein if the log reporttype indicates a non-real-time log report type, the first IDCinterference information and the second IDC interference information aretogether reported to the network after a specific point of time.
 14. Themethod of claim 13, wherein the IDC interference measurementconfiguration further comprises logging interval indication informationindicative of the specific point of time.
 15. The method of claim 14,wherein the step of reporting the first IDC interference information andthe second IDC interference information to the network comprises:receiving a log report request from the network, and sending the firstIDC interference information and the second IDC interference informationto the network in response to the log report request.
 16. The method ofclaim 12, wherein if the log report type indicates a real-time logreport type, the first IDC interference information and the second IDCinterference information are individually logged and individuallyreported to the network.
 17. The method of claim 11, wherein the firstIDC interference information further comprises information about timingof the first IDC interference measurement.